Iran´s fleet of twenty submarines poses a dangerous and unpredictable
force in the Persian Gulf region.

The United States - with its Fifth Fleet is based in Bahrain and
carrier groups frequently deployed in the region - has not revealed
what it knows about Iran´s capabilities.

Military analysts believe the U.S. has been using aircraft,
satellites, subs, and underwater sensors to monitor the activities of
Iranian subs at sea.

Doing so requires entering Iranian territorial waters, but the
Iranians would be unlikely to admit US warships entered their waters
with impunity publicly.

Recent US war games which included achieving naval dominance, air
superiority, and a coastal foothold in a fictional nation closely
resembling Iran were said to include an anti-submarine warfare
component.

But the efficacy of Iran´s submarine fleet remains unknown due to the
untested nature of most of Tehran´s designs.

Russia agreed to stop selling its Kilo-class subs to Iran in 1996,
forcing Tehran to develop homegrown craft. Tehran has three such
vessels.

After ten years of trial and error they produced the 100 ton Qadir
class vessels in 2005. Iran currently has 12 of these small diesel
electric subs. The Qadir-class vessels are squarely between the old
midget submarines and the Russian Kilos.

Analysts say look very similar to the Italian made Cosmos SX-506B
submarines that Columbia received in the 1980s. The 100-ton SX-506Bs
are only large enough to carry commandos and mines. News photos also
show what may be two torpedo tubes, as well.

Russia´s Cosmos exported a number of larger SX-756 vessels to
Pakistan in the 1990s, which may be the design basis for the Qadir.
The North Korean Sang-O class submarine closely approximates the
Qadir type.

In 2007, North Korea gave Iran four of its Yugo-type midget
submarines. These elderly Yugos are 90-ton, 65-foot craft.

Iran is also believed to possess five larger Nahang class subs. A
about 500-tons it is the same size as and closely resembled the old
German Type-206 class from the 1960´s, which was developed for
operations in the confined shallows of the Baltic.

The Type 206ís size enabled it to carry eight torpedo tubes with no
reloads, but the Iranian version has been little seen and Western
intelligence officials believe it is a failed design.

Tehran is now working on the third indigenous Iranian design. Laid
down in 2008, the Qaaem is a 1000-ton boat and should be large enough
to handle a full set of torpedo tubes along with a reload. They could
be the possible replacement for Iranís Russian-made Kilos.

Iran´s Kilo 877/636 type diesel-electric submarines pose the most
significant threat in Tehran´s submarine fleet. The 2300 ton Kilos
are long range subs capable of operating throughout the Indian Ocean.

They have six 533mm (21 inch) torpedo tubes and carry 18 torpedoes,
or 24 mines. The Kilo is regarded as a formidable foe and stay at sea
for up to 45 days. Iranian Kilo crews have more than a decade of
experience, but the craft are more than half-way past their 30-year
lifespan.

The real question is whether Iran has found ways to overcome their
limited experience and technological know-how with warship
construction in general, and submarine construction in particular.

The Qadir boats are reported to be troublesome for their crews and
unsafe, which some analysts say may be indicative of Iranian
submarine design overall.